public class Projector implements Device {
        private String brand; // 品牌

        public Projector(String brand) {
            this.brand = brand;
        }

    @Override
    public void powerOn() {
        System.out.println(brand+"投影仪开机，正在预热...");
    }

    @Override
    public void powerOff() {
        System.out.println(brand + "投影仪关机，散热中...");

    }

    @Override
    public void repair() {

    }
}
